1. Field of the Invention
This invention relates to methods of dissolving copper into electrolytic solutions, and more particularly, to methods of accelerating copper dissolution into aqueous electrolytic solutions, such as those comprising nitrogen compounds. Specifically, this invention relates to methods of supplying an anodic current to copper or copper-containing metal that is in contact with an electrolytic solution comprising an amine (such as 2-aminoethanol or 2-hydroxyethylamine) and carbon dioxide, for example, by galvanic coupling with a material having a more positive reduction potential than copper (or the copper-containing metal) given the respective electrolyte conditions present at the copper (or copper-containing metal) and present at the galvanically coupled material. Copper-containing solutions thus formed may be useful, for example, as wood preservatives and for water treatment.
2. Description of Related Art
Copper-containing aqueous solutions are commonly used as biocidal fluids, for example, for pressure treating lumber and for water purification. Examples of such fluids and uses thereof may be found, for example, in U.S. Pat. No. 4,929,454. Such solutions may be formulated by dissolving copper into aqueous solutions containing alkyl amines or alkyl hydroxy amines, such as, 2-hydroxyethylamine. Relatively slow rate of copper dissolution may be a limiting feature in the production of copper-containing solutions. When in contact with aqueous alkanolamine solutions, copper is more active toward corrosion than it is in aqueous solutions which do not contain alkanolamines. However, copper is a poor catalyst for oxygen reduction. The presence of carbon dioxide may increase the solubility of copper in aqueous alkanolamine solutions, but the dissolution rate of copper may still be relatively slow.
In one conventional batch process for producing copper-containing amine solutions, approximately five days is required to achieve the target copper concentration (i.e., about 8%). Such a process may include, for example, placing copper metal into an aqueous solution containing 2-hydroxyethylamine and carbon dioxide at elevated temperature, while sparging with air.